The very earliest KEF T27 Tweeter had a free air resonance of 0nly 900Hz.
The specification for the later models was somewhere 1300Hz if i remember correctly._________________I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

But knowing this, it is strange to me that there were no changes in the crossovers....
Apparently, both types can be used with the same type of crossover...

Regards,
Wouter

Yes, they can be used with the same type of crossover. I used 6535 tweeters in my re-built Codas without any problem. They sound just fine.
Whether the SP1032 does make a difference I don't know, but they cost more as people are looking for them to use in LS3/5as._________________M G Miles